The deployment of wireless networks, such as solutions based on IEEE 802.11, has increased rapidly, and continues to do so. In addition, the data transmission bandwidth continues to increase with new releases of WLAN technology. As a result, an ever increasing multitude of stations, most notably mobile stations, being capable of communicating through WLAN, are taken into use. This results in dense environments, where large numbers of stations may compete to gain access to the Internet or other services, through the use of WLAN.
In WLAN radio traffic is provided on a shared transmission medium. One state of the art solution used for coordinating Media Access Control (MAC) is denoted Carrier Sense Multiple Access (CSMA), which may be carried out in a variety of modes. This method involves the use in a transmitter of feedback from a receiver, to determine whether another transmission is in progress before initiating a transmission. The CSMA method may be further combined with other techniques for providing suitable coordination of data traffic. One example of such a technique is CSMA with Collision Avoidance (CSMA/CA), by means of which transmission is deferred for an interval if the channel is sensed busy before transmission, which reduces the probability of collisions on the channel. Other CSMA techniques include CSMA with Collision Detection (CSMA/CD).
With the high increase of stations competing to gain access to a WLAN Access Point (AP), there is however still need for improvement in the art of coordinating access to a shared transmission medium. One problem related to the high-density deployments of such networks is the risk of overlap of Basic Service Sets (BSSs), where plural APs are provided with at least partly overlapping communication range. Simultaneous transmission from such APs and stations in such a scenario may cause collisions, which can result in excessive management traffic and reduction of throughput.
In managed WLAN networks such as offices, public venues etc., the WLAN configuration is often such that it only allows narrow bandwidth traffic, say 20-40 MHz, to facilitate cell and channel planning. On the other hand, private networks optimized for peak throughput rather than capacity may allow up to 160 MHz channels. Similarly for the device side, some devices support wide bandwidth and some don't. Therefore, real networks include a mix of devices and access points configured for transmission at different bandwidths. This scenario may create problems, since the transmission at e.g. one 160 MHz channel will momentarily occupy a transmission channel spectrum that could otherwise have been allocated to 8 separate devices, transmitting at 20 MHz. This disclosure proposes a method to allow better coexistence and utilization of the spectrum in environments with devices having different bandwidth configurations.